1. Field of the Invention
The present invention relates to a bicycles and more particularly to a stretchable bicycle with improved characteristics.
2. Description of the Prior Art
Bicycle as a transportation means is well known. Recently, bicycle is also used as a recreation means. Hence, the structure of bicycle has become more complex. Further, a variety of bicycle types are available in which a more popular one of them is a type of foldable bicycle. Furthermore, a latest type improved from the foldable bicycle is the stretchable bicycle one. Stretchable bicycle as defined herein means a rider can adjust a length of the bicycle (i.e., distance between two wheels) by operating a stretch mechanism of the bicycle so as to fit different individuals with various heights. As a result, any rider can enjoy a degree of comfort while riding the stretchable bicycle.
A conventional stretchable bicycle is illustrated in FIG. 12 in which a crossbar of a typical bicycle having a fixed length is divided into two parts each being separately manufactured but connectable as detailed later. As shown, a front crossbar 90 can be telescopically received in a rear crossbar 91 for adjusting a length of the bicycle. A rear end of the rear crossbar 91 is fixed to a seat tube 92 by welding and a front end 93 thereof is open for permitting a portion of the front crossbar 90 to receive in the rear crossbar 91. However, the front crossbar 90 cannot project from the rear end of the rear crossbar 91 since as stated above, the rear end of the rear crossbar 91 is closed at the seat tube 92. Thus, a shortening of a length of the front crossbar 90 (i.e., the crossbar""s length) is limited. In other words, a shortening of distance between two wheels 94 and 95 is still limited. This has the drawbacks of adversely affecting storage and transportation due to large occupied space. Moreover, a fastening of the front and rear crossbars 90, 91 is effected by a single clamp device 96 therebetween. Hence, a reliable fastening of the crossbar is not possible. It is understood that a significant force is concentrated on the clamp device 96 when a rider rotates pedals 97 as the distance between the wheels 94 and 95 has been adjusted to a maximum. Hence, the front and rear crossbars 90, 91 as well as the bicycle itself are subjected to an abnormal vibration. To the worse, the bicycle may be broken into two parts if the clamp device 96 is collapsed. This is very dangerous.
Thus, it is desirable to provide an improved stretchable bicycle in order to overcome the above drawbacks of the prior art.
It is an object of the present invention to provide a stretchable bicycle which comprises a separate but connectable crossbar consisting of a sliding bar extended rearward from a front frame and a cross tube fixed to a rear frame, the cross tube being adapted to telescopically receives and permits the sliding bar to project from its rear end. A distance between two wheels, being maximum, minimum, or any length between the maximum and the minimum, can be adjusted by sliding a portion of the sliding bar inside the cross tube so as to fit different individuals with various heights.
It is also an object of the present invention to provide a stretchable bicycle that can be moved easily and is suited to transport and store in, for example, trunk of an automobile after shortening to a minimum length.
It is another object of the present invention to provide a stretchable bicycle which comprises two quick-releases and an anti-twist mechanism for fastening the sliding bar at both ends of the cross tube respectively for maintaining the structural strength of the bicycle.
It is still another object of the present invention to provide a stretchable bicycle wherein for further reducing a storage or parking space, a rider can clockwise turn the bicycle 90 degrees to stand on a supporting surface so as to form a triangle by two bent portions of a kickstand and the rear end of the sliding bar.
It is a further object of the present invention to provide a stretchable bicycle wherein the sliding bar comprises a through channel for receiving umbrella, air pump, or miscellaneous items.
To achieve the above and other objects, the present invention provides a stretchable bicycle which comprises a separate but connectable crossbar consisting of a sliding bar extended rearward from a head tube of front frame and a cross tube fixed to a support tube of rear frame, the cross tube being adapted to telescopically receive and permit the sliding bar to project from its rear end. Also, two quick-releases and an anti-twist mechanism are provided for fastening the sliding bar at both ends of the cross tube respectively. Hence, a distance between two wheels, being maximum, minimum, or any length between the maximum and the minimum, can be adjusted by sliding a desired portion of the sliding bar inside the cross tube.